From what other have pointed out, the blip is much more primitive than hail mary, and Eridian is not really a space-dwelling spices. I guess this is hinted at in the movie: the way they communicate via throwing bottles, they don’t understand Grace phoning home, and they don’t know about space radiation.

But I feel these are not properly conveyed in the movie: rocky can instantly build tunnel and adjust to environment to make it livable for human (without encountering Grace or visited his ship), and later Grace went on rocky’s ship, seems to all suggest Eridian has much more advanced technology than human.

Just a sentence in Graces log probably can set a better tune that human has more advanced tech, but Eridian are better at manufacturing.